8-Aminoguanine, a compound known since the turn of the century, has been reported to have PNP-activity by R. Parks, et. al., in Biochem. Pharm., 31 (2), 163 (1982). A synthetic method for 8-amino-9-benzylguanine was discussed at the 16th Annual Graduate Meeting in Med. Chem., University of Michigan, Ann Arbor, Mich., however, the effect as a PNP inhibitor of a guanine substituent at N-9 was not reported and is unpredictable.
The present invention is related to novel guanine derivatives, particularly, guanines as having PNP- inhibiting activity.